The present invention relates to electrically powered foldable rearview mirrors of a motor vehicle and, more particularly, to an electrically powered control system for electrically powered foldable rear view mirrors.
Conventional electrically powered foldable rearview mirrors for a motor vehicle are provided on the exterior of the vehicle for the driver so that the driver can see to the rear of the vehicle and are folded by an internal electric motor as needed or are deployed in the erected state during driving. As disclosed by Japanese Published Patent Application No. Sho 63-169341, the electrically powered foldable rearview mirror comprises a shaft mounted on an extension of a base fixed to a door panel or to a quarter window of the vehicle, a spring and a clutch gear respectively received in a frame connected to the shaft and a clutch receiver pressing the spring and thereafter being fixed to the shaft. The clutch gear is adapted to engage with a pinion gear which is rotated by the internal electric motor in a mirror body via a speed reduction mechanism and the mirror body is rotated around the shaft by actuating the electric motor.
In an erected state or a folded state of the electrically powered foldable rearview mirrors, methods of deenergizing the motor control circuit while the rotation of the mirror body is being halted by a rotation step means are described hereinbelow. In one of the methods, means for changing the circuit is provided at the rotating parts between a clutch retainer fixed on the shaft and the mirror body, so that a folding state of the control circuit is changed to an erecting state of the control circuit and vice versa and the motor control circuit is interrupted or opened, when the mirror body rotates and reaches the folded state or the erected state. In another method, a load current of the motor is detected to interrupt the control circuit.
In a conventional control system for electrically powered foldable rearview mirrors as described hereinbefore, in the control system having the means for changing the circuit as described above, it is difficult to adjust the means for changing the circuit to the erected state or the folded state of the mirror body. Furthermore because the means for changing the circuit includes; a slide contact system, there is a problem due to an imperfect contact on the rotating contact surface a foreign material contamination and the like and the circuit composition is complicated. Moreover, in the latter method of detecting the load current of the motor, because of the environmental conditions during mirror rotation, variable friction on the slide rotating surface, foreign contamination or thermal variation, a load fluctuation of the motor is caused thus making the correct stopping of the mirror body based on a motor load fluctuation criteria impossible.